Method of treating oses



"QUNITED TA E PATIENT. OFFICE...

RICHARD L. LLOYD, on NEW YORK, n. Y., assrenoa r o DWIGHT & LLOYD METAL- LunGIcAL COMPANY, on new YORK,

II. Y.','A CORPORATION OF NEW JERSEY.

METHOD or TREATING ORES.

No Drawing.

To all may concrn: Y

Be it known that-I, RICHARD L. LLOYD,

citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Methods of Treating Ores, of which the following isa specification.

This invention relates to a method of obtaining zinc from ores,-or' masses of material of either of several constitutions from which it has heretofore been'found impossible or exceedingly difiicult, to separate all of the' metal. I V

That'the characteristics of the method'to be herein presented'may be readily under stood, I will specifically mention (but merely as'a type of the zinc-bearing materials contion) 7 taining' quantities of zinc which it is de sired to completely separate), the solid resi-, due material which remains 1n a zinc l1X1Vlation apparatus after that part of'thezinc has been dissolved out which was in solubleform when introducedto the lixiviation apparatus.

The lixiviation stage is frequently fol- A mass of finely crushed zinc'sulfid ore is placed upon a furnace hearth and a shallow stratum is formed. It can be regarded as containing 40 per cent. of zinc (approxif matelyfcOurse), 25'per cent. of sulfur, 10 per cent. of silica,-together with varying persilver, etc.

centages of othermetals as iron.'lead,- gold,

, The ore stratum on the hearth, as assumed the stratum to astack. Air in regulated quantities is alsoadmitted to the region of illustratively, is subjected to the: action of streams or flowing vohunes of heated gases,

.or'products of combustion coming from an external source (asfa fire-box), relatively remote from the ore mass and'passing over the mass. The quantities of the heat applied and the oxygen are so adjusted as to form as large a proportion of .zinc sulfate as pos- ,sible, the'various.reactions'being such as Specification of IiettersP atent. Patented lay 17 1921 jApplication filed August 22, 1919. Serial No. 319,266.

usually occur during this widely practised treatment.

In practice it is found that a relatively large quantity of zinc oXid is also formed. supplemental to the zinc sulfate, even when the temperature is kept low. V

After the first treatment, thus briefly referred to, the material is delivered to the lixivi'ationapparatus. Diluted sulfuric acid ispermitted to leach through the mass. The

. zinc sulfate is dissolved out. The zinc oXid is'sulfated and becomes soluble and iscarried off in solution. 7

The fluid containing the dissolved sulfate is after theremoval of impurities subjected to the action of, for example, electrolysis for the purpose of separating the metal.

There are left in the lixiviation apparatus large quantities of undissolved material which I shall herein refer to as the liXiviation residue. is oftenfound that 20 per cent. of this residue is'zinc in an insoluble form.

To obtain this zinc, a practice, more or less crude in character, has been followed of commingling coal with the residue taken fromthe lixiviation apparatusand subjecting the mass to heat and internal combustion under such conditions that the zinc will be reduced, volatilized and carried off as fumes, which, to a greater or less extent, are condensed or collected in bags or the like.

If this residue of the lixiviation apparatus contains, as is frequently the case, commercially high percentages of other metals such as lead, gold, silver, or'the like, it is subjected to one process or another suitablefor separating such of these metals as it desired to obtain.

The present invention (disregarding these i collateral matters such as the separation of lead, gold, silver, or the hire) relates to a In treating many zinc ores it method for treating a zinc-bearing ore mass 7 in such way that all of the zinc can be separated by dissolving it out while it is being treated in the lixiviation apparatus. In one case I apply my treatment to the ore before any of it has been passed to the lixiviation apparatus. In other cases I follow the earlier steps of the series commonly followed in treatment and, then, after the stage of lixiviation, withdraw the residue and apply thereto my improved treatment I iation, have led to the opinion that the zinc is either mono or another of numerous combinations with other bodies, which combinationsare characteristic of'the minerals of the silicate and spinel groups, or more particularly in ferrite or fer-rate combination, which is quite probable in some cases. These insoluble forms .of zinc are produced in the roasting operation instead of the desired sulfate or'oxid of zinc, and in the subsequent lixiviation treatment are not dissolved.

I have discovered that that part of the Zinc component, found in almost all of the ordinary zinc .ores, which refuses to respond to the action of the solvents, is susceptible of being made soluble if it is subjected to a method of treament involving certain conditions (as to temperatures and in relation to neighboring bodies) whlch I have also dis covered and which conditions and relationships I have found how to predetermine and properly adjust or regulate.

I will first describe the manner in which I treat the residue from lixiviation obtained when the ordinarymethod is followed and above briefly referred to.

After the first treatment in the desulfurizing furnace and the production of as large a proportion of zinc sulfate as possible with, as above remarked, an accompanying proportion of zinc oxid, and, after the mass from the furnace has been lixiviated and the solution mass therein obtained has been withdrawn and purified for electrolytic treatment, I withdraw the residue, of which, as above remarked, in many cases '20 per cent. is zinc. This in suitably ground or pulverized condition is commingled with coal and the mingled mass is subjected to a second furnace treament. Some heat may :be supplied from an external source; some will be derived from the oxidizingcarbon. But one of the important factors is the holding down of the heat to the proper point. It must not, under any circumstances, for good results, be carried to the point where zinc will reduce and vaporize. It is merely raised to a point more or less short of that where zinc reduction occurs, and is maintained at this relatively low point where, as I have found, certain reactions are set 'up and the zinc component is rendered soluble when it is subjected to the lixiviation process at a subsequent step. releasing can be effected when the zinc is present in any one of its spinel combinations.

After the mass has been subjected'for a sufficient length oftime to the action of the heating and reducing materials (without reaching, as above described, the zinc reducing temperature point) it is in condition to be delivered to the lixiviation apparatus. The latter may be of. any of the ordinary forms suitable for such work. The zinc bodies now respond to the ac d solvent and are carried off in solution, the zinc in the residue being reduced to the minimum.

After this second extraction of zinc by solution, the solid residue may, if commercially justified, be subjected, as in the ordinary practice, to such treatment as is required for the withdrawal of gold, silver, lead, or the-like.

The solutiontaken away from the lixiviation apparatus may be subjected to any further treament which is suitable for separating the zinc.

Passing to the second way of using my improved zinc ore treament above referred to, that is, turning to the treatment of an ore mass which initially contains zinc in a form which is, or can readily be made, soluble and also contains it in spinel form or other insoluble form:

I will assume a zinc-bearing ore of the sulfid class in finely crushed condition. I first treat it in a manner more or less similar to that ordinarily followed in using .a desulfurizing furnace, applying the heat in such way and at such degree that the sulfid will be as completely as possible converted into sulfate onidg I then take the furnacetreated masses and mix with them a suitable reducing agent as coal. Then I subject them, in the way above described, to a relatively low temperature, namely a temperature below that at which zinc is reduced and volatilized, maintaining them at a low heat for a length of time depending upon the constitution and character of the ore. The first furnace treatment puts into'soluble condition that portion of the zinc which is ordinarily made soluble by a careful sulfatizing and oxidizing roasting. The second part of the zinc in the original mass is, by the second low-heat treatment in the presence of the reducing agent, put into the condition above described where it will also respond to the action of the solvent during lixiviation. I v

\Vhen utilizing my method in this latter manner there is required but one passage of a solvent through the mass; there being in this case no body corresponding to the zinc containing residue which involvedin describing the first use of the process.

The above description has been specific in I have found that this many respects for the purpose of clearness;

' but, I do not wish to be understood as there- Again, it is immaterial, as concerns the broader phases of my, invention, as to whether the lixiviation treatment is followed by an electrolytic action or any other that may be preferred for separating the metal from the solution.

I do not claim herein the method of treating ores which consists in preliminarily roasting the ore, subjecting the mass to the action of a solvent and then again subject ing the mass to a second heattreatment and -a subsequent solvent action, this having been made the subject of my tion No. 329,864 which present application.

What I claim is:

i1. The herein described method for'treating a zinc-bearing ore or material containing a negligible quantity of sulfur, the same consisting in mixing with a mass of such material a reducing agent, subjecting the commingled materials to a temperature copending applicais a division of the lower than that at which zinc reduces and volatilizes, then subjecting the mass to the action of a solvent and dissolving out therefrom the zinc component.

2. The herein described method for treating ore, carrying zinc and sulfur, it consisting in subjecting a mass of said ore to a sulfur'oxidizing temperature and lowering the percentage of sulfur to a negligible quantity, then commingling with the resulting mass a reducing agent, heating the mass to a temperature which is low relatively to the temperature where zinc reduces and volatilizes, then subjecting the resulting mass to the action of a solvent and dissolving outv the zinc or zinc-bearing component of the mass.

3. The herein described method of treating ore containing zinc sulfid and also other forms of zinc, it consisting in roasting the the mass to the action of a solvent and ,dis-

solving out the zinc or zinc-carrying material.

In testimony whereof, I affix my signature.

RICHARD L. LLOYD. 

